Add Geometry#line_substring.

dark-panda · Sep 22, 2023 · 1fa52d9 · 1fa52d9
1 parent f62c9ae
commit 1fa52d9
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Showing 3 changed files with 77 additions and 1 deletion.
diff --git a/lib/ffi-geos.rb b/lib/ffi-geos.rb
@@ -551,6 +551,11 @@ def self.geos_library_paths
         :pointer, :pointer, :pointer
       ],
 
+      GEOSLineSubstring_r: [
+        # *geom, *handle, *geom, start_fraction, end_fraction
+        :pointer, :pointer, :pointer, :double, :double
+      ],
+
       GEOSGeom_getXMin_r: [
         # 0 on exception, *handle, (double *) value
         :int, :pointer, :pointer, :pointer

diff --git a/lib/ffi-geos/geometry.rb b/lib/ffi-geos/geometry.rb
@@ -280,6 +280,13 @@ def line_merge
       cast_geometry_ptr(FFIGeos.GEOSLineMerge_r(Geos.current_handle_pointer, ptr), srid_copy: srid)
     end
 
+    if FFIGeos.respond_to?(:GEOSLineSubstring_r)
+      # Added in GEOS 3.12+
+      def line_substring(start_fraction, end_fraction)
+        cast_geometry_ptr(FFIGeos.GEOSLineSubstring_r(Geos.current_handle_pointer, ptr, start_fraction, end_fraction), srid_copy: srid)
+      end
+    end
+
     def simplify(tolerance)
       cast_geometry_ptr(FFIGeos.GEOSSimplify_r(Geos.current_handle_pointer, ptr, tolerance), srid_copy: srid)
     end

diff --git a/test/geometry_tests.rb b/test/geometry_tests.rb
@@ -562,7 +562,7 @@ def test_unary_union_with_precision
   end
 
   def test_disjoint_subset_union
-    skip unless ENV['FORCE_TESTS'] || Geos::FFIGeos.respond_to?(:GEOSDisjointSubsetUnion_r)
+    skip unless ENV['FORCE_TESTS'] || Geos::Geometry.method_defined?(:disjoint_subset_union)
 
     simple_tester(
       :disjoint_subset_union,
@@ -789,6 +789,70 @@ def test_line_merge
     )
   end
 
+  def test_line_substring
+    skip unless ENV['FORCE_TESTS'] || Geos::Geometry.method_defined?(:line_substring)
+
+    simple_tester(
+      :line_substring,
+      'LINESTRING (0 0, 1 1)',
+      'LINESTRING (0 0, 2 2)',
+      0,
+      0.5
+    )
+
+    simple_tester(
+      :line_substring,
+      'MULTILINESTRING ((0 52.5, 0 100), (0 -5, 0 0))',
+      'MULTILINESTRING((0 0, 0 100),(0 -5, 0 0))',
+      0.5,
+      1
+    )
+
+    simple_tester(
+      :line_substring,
+      'LINESTRING (1 1, 1 1)',
+      'LINESTRING (0 0, 2 2)',
+      0.5,
+      0.5
+    )
+
+    simple_tester(
+      :line_substring,
+      'LINESTRING (1 1, 1 1)',
+      'LINESTRING (0 0, 2 2)',
+      0.5,
+      0.5
+    )
+
+    assert_raises(Geos::GEOSException, 'IllegalArgumentException: end fraction must be <= 1') do
+      simple_tester(
+        :line_substring,
+        '',
+        'LINESTRING (0 0, 2 2)',
+        0.5,
+        1.5
+      )
+    end
+
+    assert_raises(Geos::GEOSException, 'IllegalArgumentException: end fraction must be <= 1') do
+      simple_tester(
+        :line_substring,
+        '',
+        'LINESTRING (0 0, 2 2)',
+        0.5,
+        -0.1
+      )
+    end
+
+    simple_tester(
+      :line_substring,
+      'LINESTRING (0.5 0.5, 0 0)',
+      'LINESTRING (0 0, 1 1)',
+      0.5,
+      0
+    )
+  end
+
   def test_simplify
     simple_tester(
       :simplify,